World hunger is well known to be a problem of extreme importance and is expected to become even more serious in years to come. Among possible solutions which, at present, are helping to solve the problem, are the use of chemical pesticides which prevent agricultural crops from being decimated by parasitical insects or fungi, or strangled by weeds.
It is also known that so-called growth regulators can be used to encourage plant development and increase the potential harvest. In fact, the term "growth regulator" covers an immense number of possible practical functions, which differ fundamentally from each other, such as: to facilitate or inhibit fruit or leaf fall, to avoid or simplify the pruning of fruit trees, to combat "lodging" of cereals, to produce more attractive ornamental plants that are more bushy or more floriferous, etc. Indeed, to call a product a growth regulator is an insufficient indication for the use unless it is completed by more precise information on the conditions under which the "regulator" is to be applied and the crops on which it may be used.
Thus the French Pat. Nos. 1,186,520 filed on Nov. 18, 1957 and No. 1,195,448 filed on Apr. 28, 1958 by Rhone-Poulenc Company describe the compounds of formula ##STR2## in which R' represents a CHO or CH.sub.2 OH radical and Z represents a OH radical, alkyloxy or amino which may be substituted by one or two alkyl radicals. These compounds are presented as growth substances active notably in the formation of new organs (roots) and in the formation of parthenocarpic fruit.
It is also known that certain chemicals can be used to increase the sugar content of sugar cane. Among these products, may be mentioned glyphosine, the chemical structure of which is given below: ##STR3## Its use on sugar cane is described in the Dutch patent application No. 6,915,811 of Oct. 21, 1968.
Glyphosine is the only product at present registered for this usage; however, it has the disadvantage of inhibiting the growth of the plant which often considerably restricts the yield increase provoked by its use. This is especially noticeable in regions where the vegetative cycle of the crop is short. Therefore, the need to develop a product which gives a good increase in sugar content of sugar cane with a significant increase in the sugar obtained as an end-product still remains a serious economic problem.